The present invention relates to the decomposition of solutions of hydroxylammonium salts. More particularly, the present invention relates to the decomposition of solutions of hydroxylammonium salts using a source of hypohalite ions.
Salts of hydroxylamine and their solutions are of great industrial importance as intermediates, particularly in the production of caprolactam. Further, hydroxylammonium nitrate is employed in the purification of plutonium metal, as one component of a liquid propellant and as a reducing agent in photographic applications.
Solutions of hydroxylamine and its salts which are generated, for example, as effluents require treatment prior to discharge or disposal.
Ullman s Encyclopedia of Industrial Chemistry reports that hydroxylammonium salts decompose on heating, and runaway exothermic decomposition can take place as a result of local heating. Decomposition is also promoted by heavy metal impurities, particularly, copper, copper-containing alloys and copper salts. The decomposition products of the hydroxylammonium sulfate are sulfur dioxide, dinitrogen monoxide (nitrous oxide), water and ammonium sulfate; the chloride decomposes to hydrogen chloride, nitrogen, water and ammonium chloride. Hydroxylammonium salts react with alkali to give the easily decomposed hydroxylamine. With nitrites, decomposition to dinitrogen monoxide occurs. Aqueous solutions of hydroxylammonium salts are acidic and heating for long periods at 80.degree. C. leads to slow decomposition. Solutions of hydroxylamine and its salts are radical traps, whereby ammonia and nitrogen are formed. Oxidation of hydroxylammonium salts leads, depending on the oxidant and reaction conditions, to nitrogen compounds in various oxidation states. Strong reducing agents such as zinc or iron powder form ammonia. (5th Rev.ed. Vol.A13, 528, 1989).
U.S. Pat. No. 4,927,542 issued to H. Fuchs et al on May 22, 1990, teaches a process for eliminating hydroxylammonium salts from acidic solutions by the use of manganese (IV) oxides.
The above process, however, introduces undesirable metal ions into the solutions and requires several treatment steps to achieve decomposition to where the effluent can be discharged or disposed of safely, for example, in a navigable waterway.